1. Field of the Invention
The present invention relates to a Lucent Waveguide Electromagnetic Wave Plasma Light Source.
2. Description of the Related Art
In our European Patent No. EP2188829—Our '829 Patent, there is described and claimed (as granted):
A light source to be powered by microwave energy, the source having:
                a body having a sealed void therein,                    a microwave-enclosing Faraday cage surrounding the body,                        the body within the Faraday cage being a resonant waveguide,        a fill in the void of material excitable by microwave energy to form a light emitting plasma therein, and        an antenna arranged within the body for transmitting plasma-inducing, microwave energy to the fill, the antenna having:                    a connection extending outside the body for coupling to a source of microwave energy;wherein:                        the body is a solid plasma crucible of material which is lucent for exit of light therefrom, and        the Faraday cage is at least partially light transmitting for light exit from the plasma crucible,the arrangement being such that light from a plasma in the void can pass through the plasma crucible and radiate from it via the cage.        
As used in Our '829 Patent:
“lucent” means that the material, of the item which is described as lucent, is transparent or translucent—this meaning is also used in the present specification in respect of its invention;
“plasma crucible” means a closed body enclosing a plasma, the latter being in the void when the void's fill is excited by microwave energy from the antenna.
We describe the technology protected by Our '829 Patent as our “LER” technology.
In our patent application No. PCT/GB2011/001744 (our '744 Application), we defined an LUWPL as follows:
A microwave plasma light source having:
                a fabrication of solid-dielectric, lucent material, having;                    a closed void containing electro-magnetic wave, normally microwave, excitable material; and                        a Faraday cage:                    delimiting a waveguide,            being at least partially lucent, and normally at least partially transparent, for light emission from it,            normally having a non-lucent closure and            enclosing the fabrication;                        provision for introducing plasma exciting electro-magnetic waves, normally microwaves, into the waveguide;the arrangement being such that on introduction of electro-magnetic waves, normally microwaves, of a determined frequency a plasma is established in the void and light is emitted via the Faraday cage.        
For the purposes of this specification, we define “microwave” to mean the three order of magnitude range from around 300 MHz to around 300 GHz. We anticipate that the 300 MHz lower end of the microwave range is above that at which a LUWPL of the present invention could be designed to operate, i.e. operation below 300 MHz is envisaged. Nevertheless we anticipate based on our experience of reasonable dimensions that normal operation will be in the microwave range. We believe that it is unnecessary to specify a feasible operating range for the present invention.
In our existing LUWPLs, the fabrication can be of continuous solid-dielectric material between opposite sides of the Faraday cage (with the exception of the excitable-material, closed void) as in a lucent crucible of our LER technology. Alternatively it can be effectively continuous as in a bulb in a bulb cavity of the “lucent waveguide” of our Clam Shell. Alternatively again fabrications of as yet unpublished applications on improvements in our technology include insulating spaces distinct from the excitable-material, closed void.
Accordingly it should be noted that whereas terminology in this art prior to our LER technology includes reference to an electroplated ceramic block as a waveguide and indeed the lucent crucible of our LER technology has been referred to as a waveguide; in the this specification, we use “waveguide” to indicate jointly:                the enclosing Faraday cage, which forms the wave guide boundary,        the solid-dielectric lucent material fabrication within the cage,        other solid-dielectric material, if any, enclosed by the Faraday cage and        cavities and/or empty portions, if any, enclosed by the Faraday cage and devoid of solid dielectric material,the solid-dielectric material, together the effect of the plasma and the Faraday cage, determining the manner of propagation of the waves inside the cage.        
Insofar as the lucent material may be of quartz and/or may contain glass, which materials have certain properties typical of solids and certain properties typical of liquids and as such are referred to as super-cooled liquids, super-cooled liquids are regarded as solids for the purposes of this specification.
Also for the avoidance of doubt “solid” is used in the context of the physical properties of the material concerned and not to infer that the component concerned is continuous as opposed to having voids therein.
There is a further clarification of terminology required. Historically a “Faraday cage” was an electrically conductive screen to protect occupants, animate or otherwise, from external electrical fields. With scientific advance, the term has come to mean a screen for blocking electromagnetic fields of a wide range of frequencies. A Faraday cage will not necessarily block electromagnetic radiation in the form of visible and invisible light. Insofar as a Faraday cage can screen an interior from external electromagnetic radiation, it can also retain electromagnetic radiation within itself. Its properties enabling it to do the one enable it to do the other. Whilst it is recognised that the term “Faraday cage” originates in respect of screening interiors, we have used the term in our earlier LUWPL patents and applications to refer to an electrical screen, in particular a lucent one, enclosing electromagnetic waves within a waveguide delimited by the cage. We continue with this use in this present specification.
In that application—our '744 Application—we described and claimed in first aspect, a LUWPL for our now so-called LEX technology, as follows:
A Lucent Waveguide Electromagnetic Wave Plasma Light Source comprising:
                a fabrication of solid-dielectric, lucent material, the fabrication providing at least:                    a closed void containing electromagnetic wave excitable plasma material;                        a Faraday cage:                    enclosing the fabrication,            being at least partially lucent, for light emission from it and            delimiting a waveguide, the waveguide having:                            a waveguide space, the fabrication occupying at least part of the waveguide space; and                                    at least partially inductive coupling means for introducing plasma exciting electromagnetic waves into the waveguide at a position at least substantially surrounded by solid dielectric material;                        whereby on introduction of electromagnetic waves of a determined frequency a plasma is established in the void and light is emitted via the Faraday cage;                    the arrangement being such that there is:            a first region of the waveguide space extending between opposite sides of the Faraday cage at this region, this first region:                            accommodating the inductive coupling means and                having a relatively high volume average dielectric constant and                                    a second region of the waveguide space extending between opposite sides of the Faraday cage at this region, this second region:            having a relatively low volume average dielectric constant.                        
In this specification, this is called a first aspect LEX LUWPL.